In a mobile communication standard such as LTE, uplink data on MAC level are transported in uplink shared channel (UL-SCH), using physical uplink shared channel (PUSCH) 121 in PHY layer. In the majority of use cases, PUSCH transmissions are triggered by UL grants on downlink control channel (PDCCH or ePDCCH) 111 received from a base station 110 (see FIG. 1).
Mobile communication standards like 3GPP standard require user equipment (UE) 120 to support a certain maximum transport block size as well as a certain maximum UL timing advance, i.e. a timing offset of UL transmissions 121 in relation to arrival of DL signals 111.
Furthermore, time of availability of UL grant information depends on the format of DL control channel 111, i.e. on ePDCCH usage or number of symbols in PDCCH 111.
New maximum transport block sizes (e.g. by added 64QAM support) and introduction of ePDCCH, where UL grant information is available much later than with PDCCH 111, impose a significant challenge to MAC layer to provide 101 UL-SCH transport blocks in time, i.e. within a predetermined time budget 102, especially when combined with large UL timing advances.
Since the support for maximum transport block sizes and maximum timing advance are treated as independent requirements, UE 120 implementation tends to be either overdesigned or not fully standard compliant (e.g. with respect to 3GPP), i.e. either too many resources (gate count, clock) have to be designed or the system has to drop grants.
There is a need to provide an efficient concept for a UE implementation that is saving resources and is yet standard compliant.